Windshield washer pump problems

[pleary36]

I follow you guys because I have a 77 K20, I am working on my 1972 GMC camper special and having trouble figuring out a windshield washers pump problem. I have had the truck around 10 years and the windshield washers never worked. I just retired and figured I get it fixed and was hoping someone could help me out. The wiper motor works fine so I bought an aftermarket washers pump pump and installed it, I hot wired it and it worked fine but when I installed the switch in the dash I had the same problem, wipers worked and washers did not. I went ahead and bought a new switch and installed it with the same results. With the switch out of the dash (not grounded) the washers worked and the whippers did not, as soon as you install the switch it went back to the washers not working and the wipers worked. I was wondering if possibly they were switching the ground side not the power? Any help would be appreciated.
Thanks, Pat

 

[Jgonick]

1967-1972 Chevy / GMC Truck - Wiper Motors

Maybe this video will help- about 2min 20 sec to about 4 min it describes the wiring. (3:07)

 

[Jgonick]

oops- please ignore.

 

[Chevy 88]

I would probably get the wipers working, and then add a new circuit and button to activate the washer.

 

[pleary36]

I follow you guys because I have a 77 K20, I am working on my 1972 GMC camper special and having trouble figuring out a windshield washers pump problem. I have had the truck around 10 years and the windshield washers never worked. I just retired and figured I get it fixed and was hoping someone could help me out. The wiper motor works fine so I bought an aftermarket washers pump pump and installed it, I hot wired it and it worked fine but when I installed the switch in the dash I had the same problem, wipers worked and washers did not. I went ahead and bought a new switch and installed it with the same results. With the switch out of the dash (not grounded) the washers worked and the whippers did not, as soon as you install the switch it went back to the washers not working and the wipers worked. I was wondering if possibly they were switching the ground side not the power? Any help would be appreciated.
Thanks, Pat

 

[pleary36]

thanks for the input, I will very carefully try switching the ground wire and wire the power directly to the pump and see what happens. The power comes out of the fuse box with a yellow wire to the whipper motor and jumps up to the coil on the mechanical pump running of the whipper motor. The other side of the coil runs up to the washer switch. It would think it would not work if I had power on both sides of the switch. I will power the pump from the yellow wire that is fused so hopefully I won’t burn something up.
Thanks again, Pat

 

[pleary36]

Turns out I had to switch the ground works great.
Thanks again for the help.